Device for protecting



Sept. 1, 1931. K. HOFFMANN ET AL 5 L DEVICE FOR PROTECTING FILMS AGAINSTIGNITION Y Filed uar h 27. 1950 KLUZ 50 #133355 Patented Sept. 1, 1931KURT HOFIHANN, F DRESDEN-Q AND MAX ENGELMAld'lN', OF LAUSA AT DRESDEN,GERMANY, ASSIGNOBS T0 ZEISS IKON AKTIENGESELLSGHAFT DRESDEN, 0F

antenna, GERMANY DEVICE FOR PROTECTING FILMS AGAINST IGNITIONApplication filed March 27, 1930. Serial No. 439,353.

This invention relates to improvements'in fire preventing devices,particularly devices for protecting the film of cinematographicprojection apparatus against ignition in case 8' a break occurs in thefilm band.

It is'the principal object of our invention to provide an automaticallyacting 'fire-preventing device of simple construction, yet eflicient inits operation.

10 Another object of our invention is the provision of a fire-preventingdevice automatically protecting films againstignition as soon as thefilm band breaks between its feed roller and the film-way, .and which isoperated by the enlarged loop formed by the filmcband in such cases.

Still another object of our invention is the provision of a device forprotecting film bands of cinematographic apparatus against ignition,with which means are connected to stop the motor as soon as theprotecting device comes into play.

A. further object of our invention is the .provision of a film actuateddevice for guidm a protecting shield between window and lig t-cone assoon asa break in the film-band occurs and in which the movement of theshield will operate a switch controlling the motor operation, whilesuitable means are provided to allow a resetting of the parts into theiroriginal operative position as soon as the break in the film bandhasbeen paired.

A stilljfurther object of our invention is the provision of a device ofthe above type equipped with a means preventing the ends of a brokenfilm band to ecome entangled in the mechanism." 7 Y I With these objectsin view, our device principally consistsof a protecting shield normallheldinoperative through engagement h t e nose of a lever adapted to beswung about its fulcrum as soon as a loop of ab.-

normal size is formed in the -film band due' control switch theoperation of the shield will operate this switch to 'stop the motor. Aresetting of the parts can be conveniently efiected by a suitable switchhandle.

The ends of the broken film band are prevented from becoming entangledin the mech' anism by means of a movable plate.

These and other objects and advantages of our invention will become morefully known as the description thereof proceeds and will then bespecifically defined in the appended claims.

In the accompanying drawing forming a material part of this disclosure:

The single figure illustrates diagrammatically an automatically actingfire preventing device for protecting the films of cinematographicprojection apparatus, constructed accord ng to our invention.

As illustrated, the film band 10 is guided about its feed roller 11,and'forming a 100 7 12 isguided in the usual manner throug thefilm-guides or way 13. If now the film band breaks and loop 12 inconsequence thereof will assume abnormal proportions or size, asindicated in broken lines at 14:, it will engage a curved flange 15 of asubstantially triangular lever 16 ful-. crumed at its apex, as at 17, toa part of the machine 18, and the loop will turn the lever about itsfulcrum to disengage its nose 19 so from the end 20 of one arm of atwo-armed lever pivoted intermediate its ends, as at 21, v the other armof which carries at its outer end the protecting shield 22. r

The pivot 21 carries'also a roller 23 over which is guided an elasticband 24 or the like, secured at one end to the film guide and at itsother end to the arm carrying the shield, and having the tendency tonormally hold end 20 in engagement with nose 19.

About a shaft 25 a switch, preferably a mercury switch, is turnable forstarting and stopping the motor oi the machine the lever 26 of which isconnected by means of a bar r 15, a protecting plate'30 is movablyarranged between both.

The device operates as follows:

Upon a break in the film 10 a comparatively large loop 14 will be-formedas indicated in broken lines which will engage under the flange 15 oflever 16 and turn" the same upwardly about its fulcrum 17. This movementwill disengage nose 19 of this lever from the upper end 20 of thetwo-armed lever so that the same will now be turned about its pivot 21by the pull of elastic bar 24: and W111 be swung into the positionillustrated in broken lines in which the shield will come between windowand light to protect the film.

Simultaneously by means of rod 27 the lever 26 of the switch 25 will beoperated to stop the operation of the motor.

After the film has been repaired, an operation of lever 26 in'theopposite direction will start the motor and bring the two-armed lever 28back into its original position and .the shield 22 will uncover theWindow tensioning band 24 while the lever 16 executing a downwardmovement will bring its nose 19 again in engagement with one end 20 ofthe two.

armed lever so as to set the device for another operation in case of abreak in the film band. The shield 30 will prevent the enlarged loopcaused by the breaking of the film band from entering between feedroller and triangular lever.

It will be understood that we have disclosed the preferred form of ourdevice only.

as one example of the many possible ways to practically construct thesame, and that we may make such changes in its construction as I comewithin the scope of the appended claims without departure from ourinvention and the principles involved.

Having thus described our invention what we claim as new and desire tosecure by Letters Patent is: V

1. A device for protecting the films in cinematographic projectingapparatus against ignition in case of a break in the film band formingan enlarged loop therein, comprising i a substantially triangular leverfulcrumed in the machine at its apex, an upper curved flange onsaidlever adapted to be engagedby thenlarged loop to swing said lever aboutsaid fulcrum, a protecting plate movably connected to said lever forpreventing the loose ends of the film band to become entangled in themechanism, a two armed lever pivoted intermediate its ends, a nose onsaid triangular leversnormally engaging the upper end of said two-armedlever adapted to be disengaged therefrom upon the operation of saidtriangular lever by said filmband loop, a motor control switch andconnections between said two-armed lever and the motor control switch tostop the motor as soon as a break in the film-band occurs, and a movableprotecting shield carried by the outer end of of March, A. D.

one arm of said two-armed lever for protecting the'film againstignition. I I

2. Ina cinematographic projection apparatus including its motor, filmband, feed roller and guide therefore, a protectin shield,

a two armed lever pivoted interme iate its 1 connected to said loopoperated means to prevent the loose ends of a broken film from becomingentangled inthe mechanism.

Signed at Dresden, Germany, this 4th day 'KURT HOFFMAN'N. MAX ENGELMANN.

